Freezing propane tanks

http://www.engineeringtoolbox.com/propane-butane-mix-d_1043.html

Here is a chart showing the vapor pressure properties of mixture of propane and butane.

At -30 degF, pure propane will have a pressure of 6.8 psig.

In a small container of propane, at the propane is drawn off, the pressure reduces and the temperature of the liquid propane will drop to its saturation temperature. So you draw off vapor fast enough the propane can reach -40 degF and will have no pressure.

The frost on the exterior is due to the propane in the tank being below 32 degF, so the water will freeze against the surface.

As note earlier, you have to be really cold to freeze propane to a solid.

More than likely, you are getting water vapor in the regulator or some oil which will cause the regulator to stop working. You do not want to put direct heat on the regulator, but you can use a heat lamp or a light bulb to warm it enough to work.

Ken

Hi,

Google is your friend. Propane freezes at -188 C (-306 F). At those temperatures one would have other problems!

If butane is suspected a good propane dealer up north can easily purge the tank.
I do prefer the word 'Propane' to be displayed vs. 'LP Gas' etc.

I know that in south Texas, selling propane/butane mixes as propane isn't unheard of, as few people would find out, and butane is cheaper, and any problems with burning are attributed to bad regulators.

So, someone who bought that might end up with problems when going north.

bluearc wrote:
A few years ago on a weekend trip during the winter my propane tank froze up and was useless is there any way to prevent freeze up.

The vapor temp on Propane is nearly forty degrees below ZERO, the freezing point lower than that (I have no idea how far) I seriously doubt the propane tank froze up.

Moisture can condense on the tank and freeze (32 degrees) and the regulator can have issues with low temps.

BUTANE however, is often sold as propane, epically in the south, this has a vapor temp closer to the melting point of water. IF it gets below freezing Butane is mostly useless.

Is it possible you got Butaned last time you filled up?

How to find out:

Sadly this takes a chemistry lab, but if you did, you got ripped off.. You see the reason some dealers sell Butane instead of Propane (At Propane prices) is that it is cheaper.

Frost on the exterior does not indicate the propane is frozen. Needs to be about -40 just to get propane to a liquid state. You will never see solid frozen propane.

Although in cold temps the propane may boil so slow it will not provide enough volume to run what you ask, especially a generator working hard.

Keep the tanks full and consider an electric heat pad if you will encounter these conditions on a regular basis.

Keep them as full as possible- they have to absorb heat from the surrounding air to vaporize the LP, and a full tank has more "wetted" area to absorb-

bluearc wrote:
A few years ago on a weekend trip during the winter my propane tank froze up and was useless is there any way to prevent freeze up.

Proper purging of the air (contains moisture) in the tank should help. I had one for a heated garage that froze every winter until the fuel company sent a guy who knew what he was doing.
When I got a new portable tank recently, the hardware store guy who gave it the first fill said purging wasn't necessary, but it wouldn't work until I took it elsewhere and had it purged.

We have that issue with the baby 1 lb. disposable cylinders used for the camp stove and for the Little Red Campfire. I searched online and the artists that use propane forges have this issue with the large tanks. Too high a flow...

Anyway they put the tank in a bucket of water. Warm is better, but even room temp. water will help prevent the freezing. So it's a easy fix for my small tank. Of course I could always buy the "T" and run the small appliances off the 20 lb. in the TC. That would fix the problem as well.

They also make 12 v. heating pads for a car battery. Might work.
120 v. heated pad for a baby bottle or for a diaper wipe container. Might work.
Small stick on heating pads for aquariums or reptile houses. Might work.

Try all the "heating" suggestions at your own risk b/c I'm not sure how hot would be too hot! BOOM!

I'd say water would thaw it safely and the best.

are you sure the tanks were filled with propane and not butane because butane will stop flowing at a much warmer temp than propane will